Absorbent articles, such as taped diapers or pant diapers, for example, may be manufactured by a process where discrete articles, such as a chassis of a taped diaper or a pant diaper including a topsheet, a backsheet, and an absorbent core, for example, are applied to one or more moving webs of components, such as webs of front and rear belt portions, for example, using transfer members of transfer assemblies. Often, a speed at which the discrete articles are fed into the process on a first moving carrier member is not the same as a speed of a second moving carrier member on which the moving webs of components are situated. Thus, the speed of the discrete articles should generally be changed by the transfer assemblies to match, or closely match, the speed of the webs of components on the second moving carrier member to properly apply the discrete articles to the moving webs of components without adversely affecting the process or a finished product produced by the process. In some instances, the discrete articles may also need to be turned (e.g., about 90 degrees) and repitched by the transfer assemblies after pickup from the first moving carrier member and before placement onto the second moving carrier member. A transfer assembly may have a frame defining an axis and a plurality of transfer members rotating about the axis. During such rotation, the transfer members of the transfer assembly may move past the first moving carrier member to pick up the discrete articles and move past the second moving carrier member to drop off the discrete articles.
One of the many issues with related art transfer assemblies is that they have to be run fairly slowly (e.g., 500 discrete articles per minute) to achieve suitable discrete article transfers. If the related art transfer assemblies are run at faster speeds (e.g., over 1,000 discrete articles per minute), suitable discrete article transfers may not usually be able to be achieved. If run at the higher speeds, the related art transfer assemblies may cause the discrete articles to fold over portions of themselves inappropriately, or otherwise not properly transfer, thereby resulting in disconfigured products or portions of products.
Furthermore, related art transfer assemblies typically use transfer members having arcuately shaped transfer surfaces. These arcuately shaped transfer surfaces may be suitable for pick-up or drop-off of the discrete articles, but not both. For example, if an arc of the transfer surface extends in the machine direction for pick-up and then the transfer surface is rotated 90 degrees, the arc of the transfer surface is not generally suitable for drop-off in the cross direction because the distal cross machine direction edges of the transfer surface will not be in close proximity to the second moving carrier member, thereby resulting in poor control during the transfer.
In addition to the above, if flat, or substantially flat, transfer surfaces are used in related art transfer assemblies, the leading edge of the transfer surface may be positioned quite close to the moving carrier member, the mid portion of the transfer surface may have a large gap between itself and the moving carrier member, and the trailing edge of the transfer surface may again be positioned quite close to the moving carrier member. The large gap of the mid portion of the transfer surface at the point of discrete article transfer and/or the gap variation may create many issues, such as faulty transfers and/or ruined or disconfigured products, or portions thereof, having edges or corners folded over themselves, for example. This gap variation may also cause the discrete articles to be mispositioned on webs of components on the second moving carrier member again potentially leading to ruined or disconfigured products, or portions thereof.
Another issue with the related art transfer assemblies is with the fluid control systems used to retain the discrete articles to the transfer surfaces during transfers of the discrete articles between the first moving carrier member and the second moving carrier member. Typically, a fluid pressure, such as vacuum, is either turned on or off simultaneously across the entire transfer surface. The fluid pressure can interact with the discrete components through ports in the transfer surfaces. During initial transfer of a discrete article from a first moving carrier member to a transfer surface, much of the vacuum on the trailing portion of the transfer surface is bled off to the atmosphere which consumes energy not necessarily required to achieve the transfer. During transferring the discrete article onto the second moving carrier member, the leading portion of the transfer surface may maintain vacuum even after the leading portion of the discrete article has been transferred or should have been transferred to the second moving carrier member so that the trailing portion of the discrete article remains attached to the trailing portion of the transfer surface. This can cause faulty discrete article transfers as the leading portion of the discrete articles can have a tendency to be retained to the leading portion of the transfer surfaces when it should be positioned on the second moving carrier member. This can be especially problematic at high speeds (e.g., over 1,000 discrete article transfers per minute). In other instances, the discrete articles may be blown off of the transfer surfaces by applying a positive fluid pressure to the discrete articles through ports in the transfer surfaces. This blow off may usually occur when the leading portion of the discrete components first encounters and is transferred to the second moving carrier member. As such, control of the trailing portion of the discrete articles is usually lost prior to being transferred to the second moving carrier member. This can cause faulty transfers of the discrete articles as the trailing portion of the discrete articles is not under control after blow off. This may especially be an issue when the discrete article contains stretched elastic elements that can contract when not controlled by the transfer surface or moving carrier member.
Another issue with related art transfer assemblies is the mechanism for rotation of the transfer members, which is typically a barrel cam. A barrel cam is expensive to manufacture and typically requires a great deal of maintenance, including frequent greasing and cleaning. This often requires disassembly of the machine and creates significant downtime.
What is needed are transfer assemblies, and components thereof, that can overcome the disadvantages of the related art transfer assemblies and that can transfer discrete articles at higher speeds while retaining better discrete article control at all points during the transfers.